5a ⁿ -8a^a+1 +(-2aⁿ)+6aⁿ -a ^a+1
 
=5a ⁿ -2aⁿ+6aⁿ -8a^a+1 -a ^a+1
 
=9a ⁿ -9a^a+1
 
=9（a ⁿ -a ^a+1）